Method of operating polyphase motors.



H. W. DOUBRAVA & .l. HEINEMAN.

v memo 0F ommme POLYPHASE MOTORS.

APPLICATION FILED APR- I3. 19M. 1,156,136, Patented vOct. 12, 1915.-

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3 SHEETS-SH 3 A l A ll 12 IIII WITNESSES:

TTOR/VEI H. W. DOUBRAVA & J. HEINEMAN. METHOD OF OPERATING POLYPHASE-MOTORS.

APPLICATION FILED APR- 13. I9I4.

w I 3 SHEETS-SHEET 2. Hg. 3. 8 4

WITNESSES .r INVENTORS.

Patented 001. 12, 1915.

H. W. DOUBRAVA &-J. HEINEMAN.

METHOD OF OPERATING POLYPHASE MOTORS. APPLICATION FILED APR. 13. 1914.

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Patented Oct. 12, 1915.

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UNITED STATES Parasitic IQFFKQEC HARRY W. DbUBRAVA, OF HACKENSACK. NEW JERSEY, AND JOSEPH HEINEIVIAN, OF NEW YORK, N. Y., ASSIGNORS TO WAGNER ELECTRIC MANUFACTURING- COMPANY, OF ST. LGUIS, MISSOURI. A CORPORATION OF MISSOURI.

METHOD OF OPERATING POLYIPHASE MOTORS.

' Specification of Letters Patent.

Patented Oct. 12, 18 15.

To all whom it may concern:

Be it known that we, HARRY W. DOUBRAVA and JosErH HEINEMAN, citizens of the United States'of America, residing at Hackensack, New Jersey, and New York city, New. York, respectively, have invented a certain new and useful Method of Operating 'Polyphase Motors, of which the following is such a full, clear, and exact description as will enable any one skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, forming part of this specification.

Our invention relates to polyphase motors, and its object is to enable the starting torque and current of these motors to be adjusted without the use of external appli- Qances either in the statoror rotor circuits,

thus making them adaptable to a wider range of operating conditions.

X It is usual to so arrange the inducing windings of polyphase motors as to spread each motor phase over one-half of each pole for; two-phase motors and over one-third of each pole for three-phase motors. quite uslual to subdivide each motor phase into at least two groups, which may be connected dither in parallel or in series, thus making one and the same motor readily convertible for use on two line voltages'either on 110 and 220, or on 220 and H0 volts, for example. A machine operating on a voltage for which the two groups of each motor phase are connected in parallel, can be started in that connection, when it will take a very large starting current and develop a powerful torque; or, the two groups of each motor phase can be connected in series at starting, when the starting torque will be reduced to one-quarter of that obtained in the normal running connection, with a cor: responding reduction of current. have found that the starting torque obtained in the normal running connection is usually too great, while that secured byconnecting the groups of each motor phase in series is usually too small, and our invention relates to means whereby an lntermediate torque can be readily secured.

It is also Now, we

are connected to the supply phase 3.

In carrying out our invention. we mix the motor phases at start-ing, connecting one group of one motor phase in series with a group of'another motor phase, thus each phase of the supply will be connected to one group of one motor phase in series with one group of another motor phase. By this means, we spread ea-ch motor phase over more than one-half of each pole in a twophase motor and over more than one-third of each pole in a three-phase motor. Since the number of magnetic lines produced by a wlnding is directly dependent on the voltage at the terminals thereof, and inversely proportional to the number of series-connected conductors in said winding and to the spreading co-eflicient thereof, it is clear that,

by spreading the windingover a larger por-' shows a two-pole two-phase inducing winding with two parallel connected groupsin each phase, while Fig. 2 illustrates our in: vention as applied to Fig. 1. Fig. 3 shows a four-pole inducing winding of the diamond type in its running connection, with two parallel connected groups per phase, while Fig. 4 shows our invention applied to Fig. 3.

Referring to Fig. 1, one phase of the twopole inducing winding illustrated therein comprises the groups 5, 6 and 7. 8; the other, the groups 9, 10 and 11, 12. The first mentioned groups are connected to thesupply phase 2, 3, while the last mentioned groups In applying our invention to the inducing windings shown in Fig; 1, we connect the group 5, 6 of one phase in series-with the group 11, 12 of the other and to the supply one phase in series with the group..9, 10 of phase 2,3; and connect the group 7, 8 of the other and .to thesupply phase 4, 3.

-In Fig. 3, is shown a four-pole diamond winding located in 16 slots, with two coil sides or two independent conductors, such v as 13, 14 or 15, 16 in each slot. 'Each phase lines.

of this winding is divided into-two parallel connected groups. One of the phases comprises the grou' s located between the'terminals 5, 6 and ,8 which are shown in full, They-other phase is shown in dash lines an'd comprises' the groups 9, 10 and 11, 12. The direction of-the currents inthat portion of the conductors which is located in the slots is indicated by, single circles and "single crosses for the one phase and by double circles and double crosses for the other phase, the crosses representing a direction of the currentirom front to backof the paper plane, "while the circles represent the opposite direction of the current. It is seen that each phase is distributed over one-half of each pole, as is usual in two-phase motors.

In applying our invention to a winding such as shown in Fig. 3, we connect the group 5,

6 of the full line'phase in series with the group 11, 12 of the dash line phase to the We also connect the group 8, 7 of one phase in series with the group 9, 10 of the other to. the line 4, 3 of the supply, with the result, illustrated in Fig. 4, that the spreading of each phase is now doubled,and embraces for each; pole an are equal to one pole pitch. The light dotted lines in the diagrams 3 and 4 indicate the back connections of the two diamond windings, While the points 5to 12-inclusive indicate the terminals of the machine, and

. 2, 3 and 4 show the supply wires of a three- .wire two-phase system.. v

shown, the'switch 17 of Fig. 4 establishes In the position the starting .connections above described,

' while, in its other position, it establishes the running connections illustrated in Fig. 3.

Assuming that the number of conductors connected in series ii /each. of'the groups shown in Fig. 3 is elght, the terminal voltage 100, andthe spreading co efiicient for the figure 3 is .89, then the number of lines produced by this winding will be 14.0%X, X representing the other factors, aside from those mentioned, which determine the actual number of lines. When one group of each phase is connected in series between termiv nals with one group of another phase, as shown in Fig. 4, then the number of useful conductors is raised to 16, while the spreading co-eiiicient is reduced to .6 6.' If the same voltage be applied to the terminals of this Fig. 4, the lines will be 949K.- If, on the othenhand, the two groups of each phase of Fig. 3 are connected in series, without mixing. then the number of useful conductors will alsobe raisedto 16, but the spreading co-eflicient will remain the same as before and the number of lines will be 7.02X. Since the-torque is, in each case, proportional to the square of the number of lines. then if the torque for the normal connection, shown in Fig. 3, is assumed to be 100, for example, the torque developed with two groups of each phase connected in series will be 25, and that developed in a motor connected in accordance with ourinvention and as shown in Fig. 4, will be 45.5, or about one-half of the normal as against one-fourth of the normal to be obtained with the prior known connection. The starting current will vary approximately as the starting torque.

Having fully described our invention, what we claim as new and desire to secure by Letters Patent of the United States is: 1. The method of operating polyphase motors which comprises supplying, at starting, the current-of at least one phase to inducing conductors distributed over arcs aggregating a greater number of degrees than the aggregate of the arcs over which the inducing conductors extend to which the' current of said phase is suppliedin normal operation.

-2. The method of operating polyphase motors which comprises supplying the current of each phase, at starting, to inducing conductors distributed over arcs aggregatnormal operation of the machine.

3. The method of operating n-phase motors which comprises supplying the current ofeach phase to conductors distributed over arcs aggregating720/n electrical degrees at starting and supplying the current of each phase to conductors distributed over arcs aggregating .360/n electrical degrees for normal operation.

4'. The method of operating n-phase motors which comprises supplying, at starting, the current of each phase to inducing conductors distributed over more than 360/n electrical degrees and supplying, in normal operation, the current of each phase to inducing conductors distributed over a smaller number of electrical degrees.

5. The method of operating from a polyphase supply motors provided with a plu-' ralit-y of inducing windings displaced from each-other. which comprises supplying at of the inducing windings in normal operation.

6. In combination, a source of polyphase alternating current, a'motor provided with phase of the supply in normal operation, and means for supplying current froma single supply phase to at least parts of two ing, and means for connecting the parts of each Winding in parallel and to a single supply phase in normal operation.

In testimony whereof, we have hereunto polyphas e windings, each connected to one of the motor phasesv at starting.

7. In combination, a source of polyphase alternating current, a motor provided with a plurality of inducing windings displaced. from each other and each comprising at least two parts, means for'connecting a part of one winding in series withpart of another and with one supply phase at startpresence 'of the two subscribing witnesses.

HARRY w. DOUBRAVA. [11.8.] JOSEPH HEINEMAN. [L.s.] .Witnesses:

' E. D. PIKE,

- E. W. 'GoLDsoHMmT.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0.?

set our hands and affixed our seals in the 

